- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Development of a sub-miniature gamma camera for multimodal imaging system
摘要： In the recent past, gamma-ray imaging detectors have achieved an intrinsic spatial resolution of less than 1 mm within a few centimeters of a useful field of view (UFOV). Unlike to conventional gamma cameras, which are large and heavy, the compact gamma-ray imaging detectors can improve the performances of the gamma cameras used in the various fields. In this study, we developed a sub-miniature gamma camera for a multimodal imaging system. The camera has a gamma-ray detector, miniature electronics modules, and a diverging hole collimator. The detector consisted of the sub-millimeter pixelated Ce:GAGG array and the silicon photomultiplier (SiPM) array module. We organized the miniature electronics modules according to the functions; an MPPC base board, analog signal processing board, integrated power supply board, and compact data acquisition (DAQ) base board. The diverging hole collimator widened an imaging area of the gamma camera from the UFOV of the detector. On the detector side, dimensions of each hole and septa were identical to the pixel and inter-pixel thickness of the reflector of scintillator array. For the intrinsic performance test, we acquired a flood map image of 729 (27 × 27) scintillator pixels, and the energy resolution was 18.9 % for an integrated energy histogram of 99mTc (140 keV). For the extrinsic performance test, we used the 57Co sheet source, and made a 99mTc line source using a capillary tube. The sources located at 10 cm apart from the collimator surface. The imaging area was three times wider than the UFOV of the detector. The system sensitivity was 19 CPM/μCi and the spatial resolution was 3.5 mm. The usability of the proposed gamma camera will not be confined to existing applications due to its compactness and novelty.
关键词： Sub-miniature gamma camera,Gamma camera performance evaluation,Front-end electronics,Multimodal imaging system,Diverging hole collimator
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - The Effect of Ground Truth on Accuracy Indexes in Hyperspectral Image Classification
摘要： In this paper, the effect of ground truths on performance evaluation of hyperspectral image classification is studied. The purpose is to investigate whether the accuracies in terms of three representative accuracy indexes, i.e., the overall accuracy (OA), the average accuracy (AA), and the Kappa coefficient, can be completely responsible when the ground truth is insufficient. The major contribution of this work is designing several experiments so as to subjectively and objectively analysis the influences of ground truths on performance evaluation. Furthermore, four evaluation metrics, i.e., the Pearson linear correlation coefficient (PLCC), root mean square error (RMSE), Spearmans rank correlation coefficient (SRCC), and Kendalls rank correlation coefficient (KRCC) have been adopted to measure the robustness of different classification methods to ground truths containing different numbers of labeled pixels and the location of ground truth in the image. Based on the designed experiments, a conclusion is obtained that insufficient ground truths may affect the performance of existing accuracy indexes. This underlines that over optimistic performance evaluations may exist when the ground truth contains a small number of labeled pixels.
关键词： accuracy indexes,Hyperspectral image classification,performance evaluation
更新于2025-09-23 15:22:29
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Performance characteristics of the digital Biograph Vision PET/CT system
摘要： This study evaluates the performance of the Siemens Biograph Vision digital PET/CT system (Siemens Healthineers, Knoxville, USA) according to the NEMA NU 2‐2012 standard (published by the National Electrical Manufacturers Association (NEMA)) to allow for a reliable, reproducible, and inter‐system comparable performance measurement. Methods: The new digital PET/CT features silicon photomultiplier (SiPM)‐based detectors with 3.2 mm lutetium oxyorthosilicate (LSO) crystals and full coverage of the scintillator area. The PET components incorporate eight rings of 38 detector blocks and each block contains 4x2 mini‐blocks. Each mini‐block consists of a 5x5 LSO‐array of 3.2x3.2x20 mm crystals coupled to a SiPM‐array of 16x16 mm, resulting in an axial field of view (FOV) of 26.1 cm. In this study PET/CT system performance will be evaluated conform the NEMA NU 2‐2012 standard with additional measurements described in the new NEMA NU 2‐2018 standard. Spatial resolution, sensitivity, count‐rate performance, accuracy of attenuation and scatter correction, Time‐of‐Flight (TOF) performance, and image quality will be determined. Measurements will be directly compared to results from its predecessor, the Biograph mCT Flow, using existing literature. Moreover, feasibility to comply with the European Association of Nuclear Medicine (EANM) Research Ltd (EARL) criteria will be evaluated and some illustrative patient PET images will be shown. Results: The Biograph Vision shows a transverse (resp. axial) spatial resolution at Full Width Half Maximum (FWHM) of 3.6 mm (resp. 3.5 mm) at 1 cm offset of the center of the FOV (measured with a 22Na 0.25 mm point‐source), a NEMA sensitivity of 16.4 kcps/MBq, and a NEMA peak NECR of 306 kcps at 32 kBq/mL. TOF resolution varied from 210 to 215 as count‐rate increased up to the peak NECR. The overall image contrast seen with the NEMA image quality phantom ranged from 77.2% to 89.8%. Furthermore, the system was able to comply with the current and future EARL performance criteria. Conclusions: The Biograph Vision outperforms the analog Biograph mCT Flow and the system is able to meet European harmonizing performance standards.
关键词： PET/CT,Digital detectors,NEMA,performance evaluation
更新于2025-09-23 15:22:29
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[IEEE 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Athens, Greece (2018.7.4-2018.7.6)] 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Modeling Electromagnetic Wireless Nanonetworks in Terahertz Band within NS-3 Platform
摘要： The wireless nanosensor network paradigm has seen a dramatic increase over the last decade. The envisioned concept uses the integrated machines (devices) at the nano-scale level. Those devices interact on a cooperative basis by means of principles known in wireless communication networks. Today, the design of the protocol stack for wireless nanosensor networks represents the crucial issue to be addressed. Currently available tools only support molecular-based approaches without the ability to account for the relevant impact that electromagnetic communications may have in this field. To cover this white spot, in this paper, the theoretical comparison of available simulation tools is given. Further, we focus on the Nano-Sim tool and create the scenario for wireless sensor networks (WNSN) based on electromagnetic communication in terahertz band.
关键词： Nanonetworks,Network Simulator 3,Simulation tools,Performance evaluation,Molecular communication
更新于2025-09-23 15:22:29
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Experimental Study on the Cogeneration Performance of Roll-bond-PVT Heat Pump System with Single Stage Compression During Summer
摘要： Photovoltaic thermal (PVT) heat pump technology refers to the integration of photovoltaic and solar heat pump, representing the deep exploitation and utilization of solar energy. In this paper, roll-bond-PVT heat pump (RB-PVTHP) system with single stage compression is proposed and investigated experimentally. The roll-bond-PVT (RB-PVT) unit is introduced in detail which is combined with the photovoltaic module and single-sided roll-bond evaporation heat exchanger laminating together. The designed experimental system consists of 4 pieces of RB-PVT units, 1HP heat pump unit and 150L heat storage tank, which is also equipped with various monitoring sensors to explore the system operating characteristics. Then the performance evaluation method of the unit and system is proposed. The experimental investigation on the cogeneration performance of the system in northern China during summer is carried out simultaneously, in terms of the thermal efficiency, electrical efficiency, thermal-based overall efficiency of the unit and heating COP of the system. The operating characteristics monitoring results show that the system works in a long-term stable condition during the daytime with considerable cogeneration performance. The detailed performance parameters have been given in this paper. This study demonstrates that the RB-PVTHP system has the large-scale practically feasible application value in northern China.
关键词： Single-sided roll-bond evaporator,PVT,Cogeneration performance evaluation,Roll-bond-PVT heat pump
更新于2025-09-23 15:21:21
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Statistical evaluation of corner detectors: does the statistical test have an effect?
摘要： This study explores the use of several non-parametric statistical tests for evaluating the performances of computer vision algorithms, specifically corner detectors, as a more reliable alternative to the graphical approaches that have been commonly employed to date. Using synthetic images carrying corners of different internal angles and orientations and a carefully designed testing framework, a ranking of the performances of corner detectors was established. It was found that Harris & Stephens and SUSAN out-performed more modern detectors. These are one of the few examples where evaluation of vision operators independent of the application has predicted performance in a real-world problem. A similar exercise on real images of the same patterns produced similar results and the findings of a real-world application that uses corners to identify signage were also consistent. Together, all of the tests considered essentially perform pairwise comparisons of performance, so when many algorithms are involved it is important to take account of the potential for type I statistical errors. Several approaches were evaluated and none were found to affect the conclusions.
关键词： performance evaluation,computer vision algorithms,corner detectors,non-parametric statistical tests
更新于2025-09-23 15:21:21
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[ACM Press the International Conference - San Diego, California (2018.11.05-2018.11.08)] Proceedings of the International Conference on Computer-Aided Design - ICCAD '18 - Strain-aware performance evaluation and correction for OTFT-based flexible displays
摘要： Organic thin-?lm transistors (OTFTs) are widely used in ?exible circuits, such as ?exible displays, sensor arrays, and radio frequency identi?cation cards (RFIDs), because these technologies offer features such as better ?exibility, lower cost, and easy manufacturability using low-temperature fabrication process. This paper develops a procedure that evaluates the performance of ?exible displays. Due to their very nature, ?exible displays experience signi?cant mechanical strain/stress in the ?eld due to the deformation caused during daily use. These deformations can impact device and circuit performance, potentially causing a loss in functionality. This paper ?rst models the effects of extrinsic strain due to two fundamental deformations modes, bending and twisting. Next, this strain is translated to variations in device mobility, after which analytical models for error analysis in the ?exible display are derived based on the rendered image values in each pixel of the display. Finally, two error correction approaches for ?exible displays are proposed, based on voltage compensation and ?exible clocking.
关键词： Organic thin-?lm transistors (OTFTs),performance evaluation,error correction,strain modeling,?exible displays
更新于2025-09-23 15:21:01
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Machine learning predictive models for optimal design of building-integrated photovoltaic-thermal collectors
摘要： This research article aims to examine the feasibility of several machine learning techniques to forecast the exergetic performance of a building-integrated photovoltaic-thermal (BIPVT) collector. In this regard, it uses multiple linear regression, multilayer perceptron, radial basis function regressor, sequential minimal optimization improved support vector machine, lazy.IBK, random forest (RF), and random tree approaches. Moreover, it implements the performance evaluation criteria (PEC) to evaluate the system's performance from the perspective of exergy. The use of these approaches serves the identification process to realize the relationship between the input–output parameters of the BIPVT system. The novelty of this work is that it utilizes and compares multiple learning algorithms to predict the PEC of BIPVT through design parameters. Hence, the research considers the parameter (PEC) as the essential output of the BIPVT collector, while the input parameters are the length, width, and depth of the duct, located under the PV modules, as well as the air mass flow rate. The results of the research for the statistical indexes of mean absolute error, root mean square error, relative absolute error (%), and root relative squared error (%) show values of (0.2967, 0.3885, 1.8754, and 1.5237) and (0.4957, 0.8153, 2.9586, and 2.8289), respectively, for the training and testing datasets. While R2 ranges (0.9997-0.9999) for those datasets. Therefore, to estimate the exergy performance of the BIPVT collector, the RF model is superior to other proposed models.
关键词： BIPVT,performance evaluation criteria,machine learning,predictive model,exergetic performance
更新于2025-09-23 15:19:57
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Performance Evaluation and Optimization of a Building-Integrated Photovoltaic/Thermal Solar Water Heating System for Exterior Shading: A Case Study in South China
摘要： Building-integrated photovoltaic/thermal (BIPV/T) systems can produce both electrical and thermal energy through the use of photovoltaic/thermal modules integrated with building envelope. Exterior shading is a common way to improve summer indoor thermal environment of the buildings in low latitudes. This study presents a BIPV/T solar water heating system for exterior shading of residences. In order to evaluate and optimize the system performances, a model was developed to simulate the thermal and electrical production of such system. The simulations for an example system in Guangzhou, a city in South China, were performed to investigate the influences of tank installation height and panel tilt angle on system performances. According to simulation results, the suggested tank installation height is 0.6~0.8 m. The shading coefficient ranges from 0.797 to 0.828 when the tilt angle varies from 14° to 38°. The reduction of panel tilt angle causes a certain improvement of shading performance. The annual auxiliary heat reaches the minimum when the panel tilt angle equals 28°, and the annual electric energy output changes little when the panel tilt angle ranges from 20° to 28°. Comprehensively considering thermal, electrical, and shading performances, the suggested panel tilt angle is 20°~28°. The average thermal and electrical efficiencies are respectively 38.25% and 11.95% when the panel tilt angle ranges from 20° to 28°. The presented system is a promising way to provide hot water, electricity, and exterior shading for residences.
关键词： exterior shading,BIPV/T,thermosyphon photovoltaic/thermal water heater,performance evaluation and optimization
更新于2025-09-23 15:19:57
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[IEEE 2019 International Multi-Conference on Engineering, Computer and Information Sciences (SIBIRCON) - Novosibirsk, Russia (2019.10.21-2019.10.27)] 2019 International Multi-Conference on Engineering, Computer and Information Sciences (SIBIRCON) - The Use of Spread Spectrum Signals to Increase the Noise Immunity of Optical Communication Systems Based on the Effect of LED Reversibility
摘要： Data mining applications are becoming a more common tool in understanding and solving educational and administrative problems in higher education. In general, research in educational mining focuses on modeling student’s performance instead of instructors’ performance. One of the common tools to evaluate instructors’ performance is the course evaluation questionnaire to evaluate based on students’ perception. In this paper, four different classi?cation techniques—decision tree algorithms, support vector machines, arti?cial neural networks, and discriminant analysis—are used to build classi?er models. Their performances are compared over a data set composed of responses of students to a real course evaluation questionnaire using accuracy, precision, recall, and speci?city performance metrics. Although all the classi?er models show comparably high classi?cation performances, C5.0 classi?er is the best with respect to accuracy, precision, and speci?city. In addition, an analysis of the variable importance for each classi?er model is done. Accordingly, it is shown that many of the questions in the course evaluation questionnaire appear to be irrelevant. Furthermore, the analysis shows that the instructors’ success based on the students’ perception mainly depends on the interest of the students in the course. The ?ndings of this paper indicate the effectiveness and expressiveness of data mining models in course evaluation and higher education mining. Moreover, these ?ndings may be used to improve the measurement instruments.
关键词： linear discriminant analysis,Arti?cial neural networks,support vector machines,decision trees,classi?cation algorithms,performance evaluation
更新于2025-09-23 15:19:57